Understanding an Accessory Relay Wiring Diagram is crucial for anyone looking to add aftermarket electronics or power accessories to their vehicle. Whether it's a new stereo, auxiliary lights, or a dashcam, these diagrams are the blueprint for safely and efficiently distributing power. This guide will demystify the Accessory Relay Wiring Diagram and show you how it keeps your vehicle's electrical system in check.
What is an Accessory Relay Wiring Diagram and How is it Used?
An Accessory Relay Wiring Diagram is essentially a map that illustrates how a relay is connected to control the flow of electrical power to various accessories. Relays are electromechanical switches that use a small amount of current to control a much larger current. This is vital because many accessories, like powerful headlights or sound systems, draw more power than a vehicle's existing accessory circuits can safely handle. By using a relay, the original accessory circuit only needs to power the relay's coil, which then closes a separate, heavier-duty circuit to power the accessory directly from the battery. This prevents overloading and potential damage to your vehicle's wiring harness.
The primary function of an Accessory Relay Wiring Diagram is to ensure that accessories are powered only when appropriate. For example, you might want auxiliary lights to turn on with your headlights, or a dashcam to record only when the ignition is on. The diagram outlines which wires connect to:
- The battery (for constant power)
- The ignition switch (to signal when the engine is on)
- The original accessory circuit (to activate the relay)
- The accessory itself (to receive power)
- A fuse (for overcurrent protection)
Properly understanding and implementing an Accessory Relay Wiring Diagram is essential for preventing electrical fires, blown fuses, and damage to your vehicle's sensitive electronics. It ensures that your added components function reliably without compromising the integrity of your vehicle's original electrical system. Think of it as building a dedicated, safe highway for your new electronic additions.
Here's a simplified look at the common components and their roles as depicted in an Accessory Relay Wiring Diagram:
| Component | Purpose |
|---|---|
| Relay | Electromechanical switch that controls high-current circuits with low-current signals. |
| Battery Terminal (30) | Connects directly to the positive terminal of the battery for a constant, high-current power source. |
| Ground Terminal (85) | Connects to the vehicle's chassis or a negative battery terminal to complete the relay's coil circuit. |
| Switched Input (86) | Receives a low-current signal, typically from the original accessory circuit or ignition switch, to activate the relay. |
| Switched Output (87) | Connects to the accessory, carrying the high-current power from the battery when the relay is activated. |
| Fuse Holder | Protects the circuit from overcurrents by interrupting the flow of electricity. |
To gain a deeper understanding and see specific configurations, please refer to the detailed diagrams provided in the following section.